Passive reinforcement construction method suitable for underwater cast-in-place pile

The invention provides a passive reinforcement construction method suitable for an underwater cast-in-place pile. The passive reinforcement construction method comprises the following steps that S1, a specific underwater construction position of the cast-in-place pile is determined according to design requirements; and S2, a plurality of high-pressure jet grouting piles are uniformly constructed in the circumferential direction of the center construction position of the cast-in-place pile through a high-pressure jet grouting technology, the high-pressure jet grouting piles penetrate through an underwater sludge layer, a distance is reserved between every two adjacent high-pressure jet grouting piles, the distance L between the centers of the high-pressure jet grouting piles and the center of the cast-in-place pile is equal to R + r. According to the passive reinforcement construction method for the underwater cast-in-place pile, operation is easy, use is convenient and safe, the plurality of high-pressure jet